Cooling systems such as radiators and the like are used in a wide variety of machine systems, notably in connection with internal combustion engines. Radiators employing a coolant fluid to extract heat from an engine and transfer the heat to cooling air are well known and widely used. While some means to reject heat is necessary in virtually all engines, such cooling systems occupy precious space and add weight, cost and complexity to engine systems. Cooling system effectiveness typically relates to heat exchange surface area, and thus size and weight of a given system. Engineers have heretofore found it challenging to develop suitable heat exchangers of conventional materials and construction in certain environments where factors such as size and weight are of particular importance.
A factor compounding attempts to utilize conventional heat exchangers in engine cooling systems is the recent implementation, and expected future implementation, of relatively more stringent emissions regulations. In some instances, engine manufacturers have turned to aftertreatment technology to reduce certain engine emissions, in many cases resulting in relatively bulky aftertreatment systems consuming volume within an engine compartment previously available for mounting heat exchanger and other cooling system components. Certain types of aftertreatment technology also raise the requirements for engine heat rejection. In other words, the available spatial envelope for cooling systems has shrunk, yet in many instances heat exchangers are now expected to operate more effectively.
Relatively smaller, highly efficient heat exchangers for engine cooling systems are now proposed. One drawback of such designs is that the heat exchange surfaces tend to be relatively tightly packed within the heat exchanger core. While certain of these designs work quite effectively, they have relatively smaller spaces for cooling air flow than conventional cores which tend to plug with airborne debris after a relatively brief service life. Debris within the core reduces heat exchanger effectiveness. Relatively fine dust particles stirred up during operation of off-highway construction equipment can be particularly problematic where high efficiency heat exchangers are used in such machines. One strategy for removing debris from heat exchanger cores is to simply halt machine operation, and manually remove debris clogging the heat exchanger core. This approach has been used for decades, but is obviously quite labor intensive and requires frequent machine down time.
Many cooling system designers have proposed inhibiting entry of debris into a heat exchanger core with filters. One example of this strategy is known from U.S. Pat. No. 3,344,854 to Boyagian. In Boyagian, a screen of a continuous loop of movable filter material is passed about a heat exchanger core. Incoming debris caught by the screen in Boyagian is circulated to another side of the cooling system by moving the screen so that air passed through the radiator via an engine fan can dislodge materials trapped by the screen. Boyagian's system would appear to be suitable for filtering relatively larger airborne debris such as leaves, straw or chaff, which can be relatively readily filtered via conventional screen material and blown from the screen relatively easily. A system with a highly dense radiator core, however, imparting substantial pressure drops to cooling air flowing therethrough, would likely be poorly served by a system such as Boyagian's as sufficient air velocity for clearing fine particulates would be difficult or impossible to achieve with a conventional engine fan.
The present disclosure is directed to one or more of the problems or shortcomings set forth above.